Mark 12, 28-34.
To know God, reason is insufficient. God knows Himself totally in the encounter with Him, and for the encounter reason is not enough. Only through the path of love can you know God.
‘But how can I love what I don’t know?’; ‘Love those close to you’. And this is the doctrine of the two commandments: The most important is to love God, because He is love.
But the second is to love our neighbor, but to reach the first we must climb the steps of the second: that is, through love of neighbor we come to know God, who is love. Only by loving can we reach this love. (Pope Francisco)